It is known to fasten metallic extruded building elements to other building parts, for example to create a support structure for use with a walking surface, for example a deck or floor. It is an object of a preferred form of the invention to go at least some way towards providing such a structure, although it should be appreciated that the invention is not limited to this particular use. It is in general an object of the invention to provide a product which gives the public a useful choice.